Manufacture of ether derivatives of carbohydrates like cellulose



yratented June 14, 1932 UNITE!)A STATES PATENT; OFFICE ARLIE W. SCHORGERI, OF MADISON, WISCONSIN, ASSIGNOR TO C. F. BURGESS LABORA- TORIES, INC., OF MADISON, WISCONSIN, A CORPORATION OF DELAWARE MANUFACTURE OF ETHER DERIVATIVES OF CARBOHYDRATES LIKE CELLULOSE Original application led August 14,

` This invention relates to new carbohydrate derivatives, especially cellulose derivatives, and methods for making them. It relates more particularly to the hydroxy-alphyl ethers of cellulose and especially those hydroxy-alphyl ethers in which substantially less than one hydroxyl hydrogen atom in each cellulose unit is replaced by an alphyl radical, and especially such compounds of this composition which are of limited solubility in caustic soda solutions and are practically insoluble in caustic potash solutions. This in vention relates also to an improved method for making such derivatives whereby an oleline oxide containing an ethylene oxide group react with moist alkali carbohydrate and especially moist alkali cellulose. Some of the products possess physical properties .and

characteristics suitable for the production of water-resistant, highly transparent films and lilaments, plastic mixturesainsulating goods, finishing materia-ls, etc.` Other forms are suitable for sizes, adhesives, ller for adhesives, etc. My new process permits of the production of valuable intermediate forms of products as will be explained hereinafter.

The raw materials suitable for my product and process include the following: carbohydrates such as cane sugar, starch, glucose, cellulose of all kinds, materials containing cellulose, hydrated or hydrolyzed cellulose, raw or purified viscose (cellulose partially or completely xanthated) before or after its spontaneous decomposition,l other recovered celluloses, and some derivatives of cellulose, such as partially esteriiied, alkylated,

or etherilied cellulose, and suitable conversion.

products of cellulose which are aslittle degraded or depolymerized as possible.

My etherifying agent is essentially a com,- pound containing an ethylene oxide structure. It may be ethylene oxide as such or any of the oleine homologs, such as propylene oxide, butylene oxide, amylene oxide or the higher homologs which may be reactive oxides. Mixtures of these oxides may be used. The chlorhydrins corresponding to these 0X- ides may also be used in my process to make the derivatives of my invention. Other chlorhydrins forming hydroXy-alphyl ethers 193 JSeria1 No. 475,249. Divided and this application led August 25, 1930. Serial No. 477,752.

solution and subjecting the resulting alkali carbohydrate to direct cont/act with the etherifying agent, that is, the olefine oxide, or a chlorhydrin corresponding to such oxide. These operations usually-result in an impure form of the desired carbohydrate compound. In practice,'optional subsequent operations may be .performed to purify the product vand produce itin forms which are technically "more useful.

It has been known that carbohydrates such as starch and cellulose combine directly with ethylene oxide to form compounds ,if/which may be ethers, but which apparently are consti'tuted somewhat differently than when made by my method.v The methods which have been used for their preparation are such that the products have little or no commer- ,cial value because of Various difficulties encountered in the process and their excessive cost. Furthermore, the products themselves are of such a nature that they apparently have littlepractical application. For instance, if one part of cotton linters istreated with l0 parts ethylene oxide at 100 C. for l0 hours a reaction probably occurs since the cotton linters seem to gain slightly in Weight, but the resulting product appears to be only a morev reactive form of cellulose which is insoluble in a dilute caustic soda solution. On the other hand, by my process, if sufficient of the oxide reacts with alkali cellulose at room ltemperatures a product is formed immediatev obtained by freezing the reaction product Alution of a chemical such as caustic soda.

with a dilute caustic soda solution. Apparently the caustic alkali serves as a catalyst in promoting the reaction between the cellulose and olefine oxide.

Although the ethers of this invention are described as being partially soluble in caustic alkali solutions they form at least in part socalled colloidal solutions therewith as they apparently do not form true solutions. The

ethers are dispersed by the caustic alkali, which is the peptizing agent. Throughout the application and claims when a solution of the ether in caustic alkali solutions is referred to, it indicates a ,solution which may be partially or wholly colloidal.

I have found that it is possible to produce a reaction between carbohydrates, for example, cellulose, and ethylene oxide and/or some of its homologs at room temperatures almost instantaneously, if the carbohydrate is first treated with caustic alkali, presumably to form an alkali compound therewith. The ethylene oxide or homologous oxide, preferably in gaseous form, is then brought into contact with the resulting alkali compound, preferablyat room temperatures. An exothermic reaction results which is, vigorous, especially if the alkali compound is wet. By theterm wet7 I have reference to a material containing the amount of liquid which remains after squeezing, wringing, or centrifuging out the excess liquid resulting from soaking the material in water or a water so- No excess of oxide is needed as the reaction is practically quantitative. If insulhcient oxide is added so that some of the reaction product remains insoluble in an aqueous caustic soda solution at room temperature it is necessary only to freeze the product in the caustic solution to obtain practically complete apparent solubility. Products made by reacting alkali cellulose with such oxides in proportions comparable to'those heretofore made by direct union of the oxide and cellulose have different properties indicating that specific methods of manufacture may determine specic properties in the product to meet the various uses to which -the product lmay be put.

Although hydroxy-alphyl ethers of cellulose similar to those which I have discovered have been known and described, those ethers have contained at least one hydroXy-alphyl radical per cellulose unit. not of limited solubility in aqueous caustic alkali solutions. Such prior hydroxy-ethers of cellulose have been produced by the action of chlorhydrins such' as ethylene. chlorhydrin, propylene chlorhydrin and glycerol chlorhydrins on alkali cellulose with subsequent puriication operations if a pure product was de- Those ethers were produce alphyl-hydroxy ethers` of cellulose containing substantially less than one replaced hydroxyl hydrogen atom per cellulose unit-and which are soluble in a 10% caustic -soda solution but which are practically insoluble or slightly soluble in a corresponding caustic potash solution and also are limited in their solubility in dilute caustic soda-solutions of other concentrations. With my method it is possible to`make these derivatives in pure form without using purification operations as had been previously found necessary. My improved method of reacting the alkali cellulose with the olefine oxide, especially ethylene and propylene oxides, to produce both the hydroxy-alphyl ethers of cellulose containing less than one replaced hydroxyl hydrogen atom and those containing more than one replaced hydroxyl hydrogen atom per cellulose unit, has advantages over the chlorhydrin method.

When vmaking `cellulose compounds embodying this invention, the original cellulose material, as hereinbeforev described, may be used in the dry, ail` dry, moist or wet condition. It isirst mercerized by steeping it for a suitable length of time, such as from one to ten minutes at room temperature or slightly above, in a caustic alkali solution such as a caustic soda solution, which may range from 14% to60% in strength but preferably con tains substantially less than 50% caustic soda. The mercerizing action is almost instantaneous. An equivalent caustic potash solution may be used. When using cellulose which is not dry, the quantity of water present may advantageously be considered when making `upthe caustic alkali solution. The caustic wasted in the subsequent operation. For example, Il may use approximately l5 parts by weight of caustic soda solution to one part of cellulose. The mixture may be gently agitated to insure uniform mercerization. As the caustic soda in the solution present increases above 50%, the subsequent etherifying action is slower. Not only does the increased quantity of caustic soda present appear to slow down the reaction, but also an excessiveamount of water has the same apparent effect. Therefore, I prefer to limit the Water present, yet to provide a caustic soda solution which does not contain more than 50% of alkali, and in consequence, employ an alkali cellulose for etherification which is merely wet with a solution of the desired strength and preferably of 30% strength.

After mercerization is complete, the excess caustic soda solution is eliminated by presacting constituents is carefully regulated.

Although any of the etherifying agents and cellulosic materials heretofore mentioned may be used, for purposes of illustration I first will describe in detail a process employing ethylene oxide and cotton linters or some other form of high grade alpha cellulose, and one in which refrigeration is not necessary. Those skilledin the art may readily adapt the following procedure to other cellulosic materials. Degradation of the cellulose through excessive ageing of .the alkali cellulose tends to make the etheried product water soluble and therefore must be avoided where water insoluble products are desired. Throughout the specification, when cellulose or alkali cellulose is referred to, it is understood that the cellulose has not been degraded sufficiently, unless such degradation is mentioned speci cally, to increase the solubility of the resulting ether beyond the limits set for such solubility in caustic alkali solution.

Under ordinary conditions `of' room temperature (20 C.) and atmospheric ressure, ethylene oxide (boiling at about 10. C.) is a vapor. It is usually stored and shipped under pressure in metal cylinders. It may be conducted as a vapor directly from such cylin ers to a suitable gas tight reaction chamber containing alkali cellulose, the rate of flow being regulated in consideration of the rate of absorption by the alkali cellulose. To`

regulate the quantity of ethylene oxide used the cylinder may be supported upon weighing apparatus suitable for indicating its decrease in weight. The ethylene oxide vapor also may be conducted directly to the alkali cellulose from an oxide generating chamber or it may be generated in the alkali cellulose reaction chamber if desirable. Evacuation of the reaction chamber prior to the introduction of the oxide is desirable since itl hastens the reaction and results 1n a more uniform etherification. Ethylene oxide isvintroduced.

into the reactionvchamber at a rate somewhat in excess of the rate of absorption and after a sufficient quantity has been introduced, the

-flow is stopped. The mixture is agitated sary, however, to keep the temperature below the 45 C. specified since it only is necessary to avoid charring, which does not take place until a considerably higher temperature (about 100 C.) is reached. Stirring also ensures that the ethylene oxide will reach all of the alkali cellulose.. The etherifying operation may be continued until the supplied quantity of ethylene oxide is absorbed. Where it is not desirable to refrigerate the the resulting ether to secure practically complete solubility in dilute caustic soda solutions it is necessary to react about 11% to 20% or more of ethylene oxide (based on the cellulose in the alkali cellulose) with the alkali cellulose. If the refrigeration is practiced the larger amount of ethylene oxide may be reduced. Ahigh grade cellulose such as cotton linters requires a larger amount of ethylene oxide to secure complete solubility than a highly purified cellulose made from wood pulp, the latter apparently being less resistant chemically.

The product obtained by the process outlined hereinabovc probably is an impure ether of cellulose and ethylene oxide having a glycol structure, one impurity being the caustic alkali which, although present to ensure success of the process, probably does not enter into the reaction directly and, after the reaction is complete, remains as an impurity. Where about 14% to 15% of ethylene oxide based on the cellulose content is supplied and absorbed it is probable that two units of cellulose are combined with each molecule of ethylene oxide; hence the probable appropriate chemical designation is ethyleneglycol(di) cellulose or dicellulosehydroxyethyl ether. A unit of cellulose is here defined as CGI-T1005.

Theoretically the ethylene oxide content of the di cellulosehydroxyethyl ether as represented by the formula below is 13.6% of the cellulose content. When less than 15% of ethylene oxide is used the reaction between the alkali cellulose made from cotton linters or other form of high-grade alpha cellulose and the ethylene oxide at about 0 C. must be carefully controlled so that only a small amount of residue insoluble in a dilute caustic soda solution remains. Under the most carefully controlled conditions I have made a compound with 11% to 12% added ethylene oxide which was practically totally, soluble (to the eye) in a 10% caustic soda solution. Even under these conditions the microscope shows that the compound may not be entirely dispersed and the ether may not be suitable for the highest grade products where a high degreev of transparency is desirable. Under ordinary conditions of reaction it is necessary to supply about 18% to 20% of ethylene oxide l for complete solubility (using a high-grade cellulose) in dilute caustic soda solution, provided the reaction product is not subjected 'to a temperature below freezing in the presence of the caustic soda solution.`v Itis possible thatsome of the cellulose units may absorb more or less than the calculated amount of oxide. Furthermore, the ethylene oxide may form a limited amount of ethylene glycol or `diethylene oxide. These facts may account gen atom of hydroxyl groups (preferably primary) of a cellulose unitor of two or more linked cellulose units whereby one valence of the oxygen atom of the oxide is'replaced by an hydroxyl hydrogen atom of the cellulose molecule to form an hydroxyl group attached to the ethylene radical. It is believed that the reaction for the dicellulose ether takes place as follows:

definitely without deterioration.

After washing, it may be dried and shipped in such fibrous form or it may be'stored in- In this form it is light, fluffy, and very easily handled. The dicellulose compound and those compounds containing a greater proportion of cellulose are insoluble in water, alcohol, and a brine comprising a saturated solution of sodium sulphate slightly. acidifiedA with sulphuric acid. The ethers of my invention differ from the ethers made previously and described in the literature and patents with respect to their solubility in caustic alkalies. My ethers made by absorption of less than 20% of ethylene oxide by the soda cellulose, based on the weight of the cellulose, are only partially soluble (less than 95%) in solutions containing more than 20% of caustic soda and in practically all vstrengths of caustic potash solutions. If less than 5% of theether is insoluble it is regarded as substantially soluble. These ethers likewise are only partially soluble in caustic soda solutions containing less than from 2% to 6% of caustic soda, the ethers higher in Vethylene oxide content being more soluble in the weaker caustic soda solutions. The reverse is true when the caustic soda solutions are in the lrange be- Cellulose Ethylene oxlde The foregoing illustrates the reaction on a primary hydroxyl group. More generically expressed, the reaction is undoubtedly Where X.OH represents the carbohydrate or its derivative.

The reaction for other carbohydrates such as starch, sugars, glucose, etc. probably takes place in a similar manner. When more ethylene oxide is absorbed than that shown by the above equation it is probable that the oxide replaces hydrogens in additional hydroxyl groups of the carbohydrates or it forms chain compounds with the hydroxyl of the added ethylene radical. Thus 'in further reaction it is possible that two different products are formed or a' mixture of two different products are formed. In the refrigeration method to be hereinafter more fully described, it is` probable that one ethylene, oxide molecule or hydroxy-alphyl radical combines with aggregates consisting of four cellulose units. The aggregate suffers less degradation when less oxide or alphyl radical is added.

If acidified and then washed free of the resulting salts and remaining acids after such operations as have been described, the products retain the physical form and megascopic structure of the material from which it is derived, that is, in this case, the fibrous structure of cotton linters or other alpha cellulose.

. Dioellulosehvdroxyethyl ether tween 15% and 20%. The greatest solubility seems to be in' 5% to 15% solutions of caustic soda with the maximumat about 10%.l These same ethers containing up to about 20% of added ethylene oxide are but partially soluble in caustic potash solutions of any strength. Of these ethers, those containing from 13% to 14% to about 20% of added oxide, though only lpartially soluble; show the largest solubility of any of my ethers in caustic potash solutions of about 15% to 20% concentration, although most of them are less than 50% soluble. The ether solubility or dispersion in a caustic alkali solution apparently increases more or less directly with the concentration of the etherifying agent.l

However, the solubility or dispersion of the ether mayvary over a wide range in a small range of caustic alkali concentrationA as is shown in the accompanying solubility curves.

At about an 8% ether concentration the clear solution is highly viscous so that solutions of much above that concentration are of little interest.

The solubilities given above and as defined for the claims are based on measurements made at room temperatures and on both dry and moist ethers made from alkali celluloses in which the cellulose has not been subjected' v to the action of caustic alkalies for an excessive length of time, that is, the cellulose has not suffered enough degradation to make the resulting ethers appreciably more soluble. n

Alpha cellulose derived from wood pulp is the basic cellulosic material. The solubilities are determined Vby exposing the dry or wet precipitated ether to the action of the caustic alkali solution for 24 hours at room temperature, the weight of ether conveniently being 2% of the solution weight. The solution is then centrifuged in an ordinary laboratory centrifuge. The solids thrown out of .solution ,are washed by further centrifuging, thrown vinto a coagulating bath (alcoholacetic acid mixture), ltered', dried, and weighed. That portion of the ether which is 'thrown out of solution since it is not sufficiently dispersed to form a clear to the eye) colloidal suspension or solution is regarded as not .soluble since lsuch undissolved ether cannot be tolerated commercially where clear solutions are required. For Vspecial purposes a greater degree of dispersion may be required. The ether apparently disperses to varying particle sizes according to its concentration in the caustic alkali solutions. It disperses to a finer state of division, therefore indicatingr a higher solubility, the lower its ratio to the solution. The greater the dispersion the smaller the amount 0f ether which is thrown out by centrifuging and the higher the apparent solubility. I have accordingly used a low ether concentration .when determining the .solubility thereof since solutions of such low concentration are below those of any commercial importance, and, furthermore, a limited solubility of .the ether in such concentrations indicates a much lower solubility in those -concentrations of commei-cial importance. The solutions of low ether concentration are also less viscous Aand more amenable to the necessary manipulations.

The ethers should be .substantially soluble in dilute caustic soda solutions if they are to be used directly and are to be of any commercial importance where transparency and freedom from insolubles is required. Practically all commercial solutions are viscous and 5% of insoluble ether in such a viscous solution prevents it from being filtered to remove any considerable amount of insoluble matter or otherwise manipulated effectively. For instance, if the ether is not sufficiently sol uble in caustic alkali solutions, a film made therefrom is not clear and transparent. or if the .soluble portion is filtered off after diluting thesolution sufficiently to make it filterable. it does not form a usable film because of the low ether concentration. Such low concentration solutions also cannot be used for making imitation silk fibers. A film made for 4commercial,purposes should have a thickness of about .001 inch when dry. A. .solution containing at least 5% of the ether is usually required to make a satisfactory film. The solution should be practically clear to the eye though it may even then contain insuficiently dispersed cellulosecompounds which may prevent the making of a high grade product. The solubility of the ether in caustic alkali solutions may be increased by freezing it in the presence of caustic alkalies provided that the ether is subjected to the action of the solvent caustic alkali directly after freezing, that is, the ether is not precipitated out of the alkali Vafter the freezing operation. The freezing operation disperses the ether more effectively and clear solutions are obtained more easily.

Whenever dilute caustic alkali solutions are mentioned in this specification they relate specifically to solutions containing from 2% to 25% of caustic alkali and sometimes may refer to solutions containing from 5% to 15% caustic alkali, especially in connection with lcaustic soda solutions.

Not only is the product containing a lower amount of ethylene oxide less soluble in dilute caustic alkali solutions but it is also cheaper to make because of the relatively high cost of the etherifying agent. It also has superior properties for many purposes. As hereinbefore described, the product formed by the absorption of less than about 11% to 15% of ethylene oxide generally does not form a clear solution when dissolved in a dilute caustic soda solution due to the incomplete solubility of the reaction product. This residual insoluble reaction product in the dissolved ether is objectionable for most purposes and must be removed. l have discovered that it may be made more soluble or entirely soluble by a Asuitable freezing operation. Itis practically impossible to filter eis this insoluble product (usually gelatinous fibers) from the viscous solutions of the ether in caustic soda which are required in the arts, and therefore other methods must be used.

In the accompanying drawing:

Fig. 1 illustrates the apparent solubility o a series of ethers in caustic soda solutions;

Fig. 2 illustrates the increased solubilities over those in Fig. 1 produced bythe freezing process of this invention;

Fig. 3 illustrates the apparent solubilities of a series of ethers in caustic potash solutions;

Fig. 4: illustrates specifically the effect of freezing to increase solubility.

I do not intend to bind myself closely to the properties of the ethers as indicated by the curves in the figures, since the properties are variable and are determined by the various factors herein described. The curves 'are given only to illustrate properties graphically for visualizing the numerous general statements herein made, and to permit one to recognize the direction in which the properties change with changes in the process.

The data for curves which appear in full lines have been rather quantitatively found to locate the same on the chart. The dotted line servations, and considerable experience within the ranges covered, and represent generally what I believe to exist.

In Fig. 1, the curves are derived, as by a standardized test, by subjecting two parts by weight of an ether containing various amounts of ethylene oxide to solution in 100 parts by weight of various strengths of caustic soda. The percent of the exposed ether which is dissolved or dispersed in the 'caustic soda is plotted vertically against the strength of thecaustic soda solution. Curve 10 corresponds to the tetra-cellulose ether, containing about 6.8% ethylene oxide. Curve 11 corresponds to a dicellulose ether containing about 13.6% .ethylene oxide. Curve 12 corresponds to a mono-cellulose ether containing .27 .2% ethylene oxide. Curve 13 corresponds to a more complex ether containing 40.4% lethylene oxide.

Fig. 2 is derived in the same -way as the curves in Fig. 1, but the product was frozen, as elsewhere described. to increase the solu'- bility. Curves 14, 15 and 16 correspond respectively to the materials of curves 10, 11 and 12 of Fig. 1. The two figures show the increase inl solubility which is most notable in the more dilute caustic soda solutions.

Fig. 3 relates to caustic potash solutions and indicates the lessened solubility therein. Curve 17 represents a dicellulose ether without freezing, and curve 18 indicates the increase over 17 by freezing the product. Likewise, curves 19 and 20 indicate respectively the relative solubilities of a mono-cellulose ether, unfrozen and frozen.

In Fig. 4 twov curves are shown based upon the following table of data Solubility of an ether conta/ning 8% ethylene oxide in caustic alkali solutions The ether was practically entirely insoluble at room temperature in 8% KOH.

Curve 21 represents the amount of undissolved ether at the various concentrations when solution is effected Without freezing..

When the same solution is frozen, as herein described, the insoluble portion is `substantially all rendered soluble over the range iudicated. The curve 22 represents the small amounts found undissolved after freezing. The shaded area 23 therefore represents graphically the advantage of the freezing process.

The low partial solubility of`my ethers in caustic potash solutions is also of further technical importance. If cellulose is mercerized with caustic potash and then etherified the resulting ether may be washed directly with water to remove the caustic potash contained therein since the ether is practically insoluble in most caustic potash solutions. This is not possible with the ether made from soda cellulose. The use of the caustic potash therefore obviates the necessity of neutralizing the caustic alkali in the ether with an acid which makes it impossib'le to recover the alkali. On the other hand the caustic potash solution washed from the ether etherification process that they require onlyl the change, perhaps only a mechanical disintegration, produced by freezing to disperse and render them apparently and effectively soluble inthe caustic soda solution. In this way I may make a product practically completely soluble in dilute caustic soda solutions (5% to 15%) although containing only about 7 to 8% of ethylene oxide' based on the weight of cellulose used. As an example, an ether containing 8% ethylene oxide, when subjected to the action of 12% times its Weight of 8% caustic soda showed 34.1% insoluble in 24 hours at room temperature. A

similar mixture when'subjected to a temperature of -20o C. for the same length of time showed but 1.20% insoluble. This indicates that one ethylene oxide unit combines with four lunits of cellulose to form ethyleneglycol (tetra) cellulose or tetracellulosehydroxyethyl ether in which compound the oxide is in the proportion of 6.8% of the cellulose content. With' less than this amount of oxide a more or less cloudy solution is formed,

even when the ether is dispersed by freezing, showing that a portion 'of the cellulose ether compound or reaction product is insoluble. I have, however, made reaction products containing as low as added ethylene oxide which, with freezing, are largely soluble iu Vau a 10% caustic soda solution. Such solutions containing undissolved cellulosic materials in suspension may be technically useful and are within the scope of my invention. As another example, an ether containing 12% to 14% of added ethylene oxide' may appear completely soluble to the eye but contains dispersed particles sufficiently large to prevent making a product of the highest degree of transparency. A freezing operation will further disperse these particles to ,produce a solution which yields lms of the highest transparency.

The compound formed which conta-ins less than 13.6% of added oxide necessary for the ethyleneglyco-l (di) cellulose ether and especially the compound containing less than 10% of added oxide or more than about 3 units of cellulose has many desirable properties. The cellulose compound of ethylene oxide of the'seproportions which, when thrown out of solution when the alkali solution reacts with an acid o-r otherfprecipitating agent, 1s tougher and stronger than one which contains a higher percentage of oxide.. It gives a film which is flexible and may be stretched without the addition of glycerine. The superior physical properties of the product indicate that the cellulose has undergone little degradation. It furthermore makes possible the use of various chemical wood pulps for the manufacture of high grade films and filaments now only possible when made with specially prepared wood pulp or cotton linters.

Films and filaments and the like may be made from the hereinbefore described ethers containing an ethylene oxide content up to 20%. If the added ethylene oxide isin excess of approximately 20% of the weight of cellu- 1 lose in the alkali cellulose the films and filaments become softer and slimier when wet. The greater the excess of oxide the more pronounced these characteristics become. Furthermore, with increased alphyl content the l product tends to become more soluble or entirely soluble in caustic potash solutions, very dilute caustic alkalies and Water. This or- .di'narily is not desirablefI I therefore prefer and about 5% caustic soda for one which hasv had to be frozen in order to make all of the ether soluble. Sufficient caustic soda solution l may be used to produce a solution containing ilar to that employed in the manufacture of films, filaments, and the like from viscose,

namely. of the approximate composition: fj.;

10% sulphuric acid, 20% sodium sulphate and the usual organic compounds such as glucose, and inorganic salts such as zinc sulphate, magnesium sulphate, etc. The product sets into a transparent, non-fibrous, solid substance which, after washing in water has a good wet and dry strength. Threads and sheets made from the new product possess good physical properties. The films or filaments so made are clear and uniform in color, often do not require bleaching, are hard and hrm in texture, and possess good tensile strength.

Following is an example in which refrigeration is used. The cotton linters or chemical wood pulp are mercerized in the usual manner as hereinbefore described. The excess caustic alkali is removed as described. The alkali cellulose is exposed to the desired amount of ethylene oxide-say not more than 6.8% to 10%-until the oxide is absorbed. Water is added to this product until the strength of the caustic soda solution the cellulose ether not included) is reduced to 2% to10%, preferably 4% to 6%, the optimum being about L1.753743. Caustic soda solutions of 2% to 10% strength start freezing at from 0.30 C. to 10 C. Tf sodium chloride or other salts are present in the caustic soda solution the percentage varies accordingly from those given. The mixture is refrigerated to such a temperature that a mass of crystals of ice form and preferably until the caustic soda solution freezes. Although the water starts freezing and ice separates from a solution containing less than 20% caustic soda the residual caustic soda solution itself does not freeze until a concentration of 20% is reached. A 20% caustic soda solution freezes at -200 C. This temperature is the most leffective. Lower temperatures may be used.

Long exposure to these low temperatures is not harmful to the product. The frozen mixture has a cheesy consistency and contains ice crystals and hydrated caustic soda crystals if the temperature is maintained at "-200 C. or lower. The mass is allowed to melt and come to room temperature. If necessary more caustic soda is added, and preferably to the melting mass to prevent geling at 1311 reaction product.

tions, is practically free from insoluble cellulosic materials and may be treated in much the same manner and used for many of the saine purposes as the product obtained when 13% to 20% of the ethylene oxide is present 15 in the compound.

Its superiority for certain purposes has been discussed previously. Although a specie procedure has been given the amountof ethylene Oxide and the refrigerating tempera- 90 tures may be varied over a wide range to secure specific products without departing from the scope of my invention. Refrigeration sometimes may be used to advantage for products containing a high percentage of oxide if a small amount of insoluble cellulosic material remains after dissolving the reaction product in a caustic soda solution.

In the above example in which refrigeration is used the cellulose is mercerized with a 25T/E) to 30% caustic soda solution, and then squeezed to remove excess caustic solution. After etherification when water is added to decrease the caustic soda concentration to about 4.7 5% for the freezing operation, the

ether concentration in the final solution is too low (about 5% to 6%) for many purposes. The preferred procedure which may be used to increase this ether concentration, and which decreases the amount of material o which has to be frozen, is to remove about 'l/; of the reaction product after etherification before dilution with water, and neutralize the alkali with acid. The ether is then washed and is added to the balance of the T'he entire mass is then diluted with water to reduce the caustic soda solution strength to 4.75%. It is then frozen, after which it is thawed with proper caustic soda addition. This produces an ether con'- centration of 8% to 8.50% which is desirable for many purposes. If desired the entire reaction product may be first acidified, washed, and then frozen in caustic soda solution.

Although caustic soda is the specific caustic 5 alkali specified during the refrigerating operation it is possible to use caustic potash so lut-ions though the concentration limits are narrower. It is possible by the refrigeration method to increase somewhat the very limited o solubility in dilute caustic potash solutions (10% to 25%) ofthe ethers containing a low percentage of hydroxy-ethyl radical. These ethers which show an increase in their very limited solubility in dilute caustic potash solutions after freezing, do not retain this inof insoluble reaction product from hydroxyethers containing a low percentage of hydroxy-alphyl radical by dissolving the etherified reaction product in a dilute caustic soda Asolution (about 6% to 10%) and filtering off the small amount of insoluble matter. The ether concentration, however, must be low tof filter the solution. As this procedure results in a solution of ether too dilute for most purposes it is necessary to evaporate ofi' the excess water or to precipitate the ether from it. After precipitation and washing it is redissolved to the desired concentration in caustic soda solution. Refrigeration may be used to aid solution. This method has too many disadvantages for practical purposes and also tends to degrade the cellulose,thereby increasing the solubility of the final ether in caustic alkalies.

It is possible also to react the ethylene 0X- ide with cellulose directly with or without a catalyst as has been previously known in the art, and then refrigerate these products with caustic soda solutions, thereby rendering soluble, or increasing the solubility of, those compounds of ethylene oxide and cellulose which have been regarded as insoluble in caustic soda. I have treated wood pulp with 12% of ethylene oxide, using a temperature of 100 C. and pressure, in t-heabsence of alkali, producing a product insoluble in dilute caustic soda solutions at room temperatures. The entire reaction product was' then frozen in a dilute caustic soda solution and on melting the solubility of the product in dilute caustic soda solution seems to have increased, judging by the increase in the amount of gel-like material. Y

I am able by my improved process to make those compounds which are lowest in cost and most useful in the arts and which apparently were not produced by the processes heretofore known.` Those compounds which were not previously produced and which are most valuable are those which are insoluble in water and practically or almost insoluble in dilute caustic potash solutions, and which have a limited partial solubility in dilute caustic soda solutions as hereinbefore described, and which contain substantially less than one molecular weight of olefine oxide in combination with one unit of cellulose (CGHNO), and especially those containing less than one molecular weight of oxide to two units of cellulose.

Although hydroxy-alphyl ethers of cellulose have been made by reacting upon wet alkali cellulose with a halohydrin of a polyalcohol the ethers resulting from that reaction have been described as being easily soluble in aqueous caustic alkalies and as being derivatives in which at least 611e hydroxyl hydrogen atom of the cellulose is replaced by an hydroxy-alphyl group. The relatively large amount of ether-forming compound thus introduced into the cellulose molecule by the above method apparently resulted in the production of derivatives which showed a high solubility in the caustic alkalies. Such compounds are of little commercial importance. I have found that it is not necessary to use the halohydrin since I apparently can produce the same compounds by utilizing the gaseous oxides which result when the halohydrin reacts with caustic alkali. I also have found that it is possible to apply the refrigeration principle to the cellulose derivatives formed by treating the alkali cellulose with the halohydrin.v

Olefine chlorhydrin, such as propylene and ethylene chlorhydrins, and glycerol monochlorhydrin, also known as alpha monochlorhydrin, may be used to produce the hydroxyalphyl ethers. The glycerol oxide corresponding to the glycerol monochlorhydrin is very difficult to make and therefore is not at present of importance for the commercial production of the dihydroxy-propyl ether of cellulose. If hydroxy-ethers 'are to beproduced which have substantially less than one hydroxy-alphyl radical per cellulose unit I have found that good results can be obtainedl by using these chlorhydrins in practically dehydrated condition. .It is also better to use a stronger caustic alkalissolution for mercerizing the cellulose. Instead of using the 30% solution which I refer with the ethylene oxide method I pre er using about a 40% caustic soda solution. If the commercial ethylene chlorhydrin, which contains about 60% water, is used, the results may be unsatisfactory and the reaction incomplete. A large amount of cellulose apparently remains unacted or only slightly acted upon by the chlorhydrin. The derivatives made by using the chlorhydrins and containing a large proportion of cellulose to'the ethylene oxide or hydroxy-alphyl content, that is, from two to four cellulose units to on'e of the oxide, contain a certain amount of cellulose reaction tic soda solution and it becomes necessary to freeze the solution as previously described to make these insoluble products more soluble. The soda cellulose after being treated with the chlorhydrin contains not only the hydroxy-ether and the insoluble particles of cellulose compound but also the sodium chloride which is formed by the chlorine in the chlorhydrin. This mixture may be frozen directly without the removal of the sodium chloride or the mixture may be neutralized,

washed to remove the sodium chloride, and

then frozen. These procedures will be further illustrated in specific examples.

Using cotton linters as a base the viscosity of the product when dissolved in dilute caustic alkalies often becomes excessive for ordinary purposes. I| find thatthis viscosity can be reduced and the tendency to solubility in water increased to any desired extent without changing the concentration of the solution, by ageing the alkali-cellulose before etherification or by ageing the unwashed and undried etherified alkali-cellulose before solution, or even by simply ageing the resulting alkaline solution ofthe ether. Higher temperatures in ageing produce a lower viscosity, and increase the solubility. Excessive lowering of viscosity may result in derivatives that produce weak lilms or filaments. Higher temperatures in the etherication do not `appreciably increase solubility. rIhere seems to be no direct relation between viscosity and solubility, but depolymerization of the cellulose both lowers viscosity and increases solubility. Higher proportions of oxide lower viscosity and increase solubility.

As mentioned heretofore, I may use cellulosic material other than cotton linters. Cotton linters are probably the least depolymerized form of'cellulose obtainable. If a more depolymerized form such as chemical wood pulp is used, the ether obtained is made water soluble more easily, the solubility increasing with the extent of de olymerization of the raw cellulosic materia-ii However, even depolymerizzed celluloses such as artificial silks, consisting of cellulose regenerated from vicose solutions, form water insoluble products if treated with moderate amounts of ethylene oxide in the presence of caustic alkali. Such cellulose (without mercerizing) forms water l soluble products with ethylene oxide directly if heated with an excess of oxide at 100 C. for a number of hours, whereas the same treatment with cotton linters or wood pulps results in a product which cannot be distinguished from the original cellulose except that it is only slightly more reactive (e. g. to esterification) but it is not soluble in water, caustic soda, or organic reagents at ordinary temperatures. The etherifying action which 11 occurs When the oxide reacts with the alkali cellulose therefore must be different than when the oxide reacts directly on the cellulose. There are many practical industrial applications for a water soluble product, in a dry fibrous form or in aqueous Vsolution. Some of the uses to which it is applicable are: size for textiles, adhesives, filler for adhesives, base for explosives, etc.

The formation of a water soluble product from alkali cellulose depends on the kind of cellulose (wood cellulose, hydrocellulose, etc.) and the ageing of the alkali cellulose, or ether solution, etc. as previously explained. The 130 rocess for producing the soluble product rom ordinary pul is simple. The raw cellulosic material suc as chemical wood pulp is Y mercerized to obtain alkali cellulose, allowed to stand for 24 hours in limited contact with air, and ethcrified with a large amount (75% to 90%- or more) of ethylene oxide as above described. The oxygen of the air oxidizes the cellulose and renders it more easily dispersible. In permitting contact with air the material is best maintained in a loose lluiy condition in a container having a loosely fitting cover through which air may enter. Further standing in contact with excess alkali may be necessary. To form the dry, fibrous product, the impure ether is neutralized with a suitable acid, Washed with alcohol, and dried. To form the aqueous solution the impure ether is dissolved in water or caustic alkali solution. It then may be neutralized with suitable acid such as acetic acid, and the resulting salts may be Washed out with an organic solvent such `as alcohol, or may be removed by dialysis or by drying the neutral product and leaching the salts therefrom with` quire neither desulphurizing nor bleaching..

An additional advantage is realized by'redissolving waste and scraps in a caustic alkali solution andy using it `for any desired purpose for which a fresh solution may be used. Furthermore no odors nor poisonous gas are liberated by the coagulating bath. Viscose must always be fashioned into its final formafter a period of carefully controlled ageing whereas my ether, once purified and freed from caustic soda, may be stored indefinitely in the dry state, or in water if a mold preventive, such as formaldehyde, is present. It may be used-at any time. .In the presence of dilute caustic soda solution, the solution shows relatively little change with age as compared to similar viscose solutions. Of course, either product may be stored safety ofrefrigerated. Furthermore, the sodium cellulose xanthate, of which viscose is comprised, is unstable and is subject to spontaneous decomposition, whereas my product is relatively stable and suffers only a slight drop in viscosity While ageing in dilute caustic soda solutions. A further advantage of my product lies in the ease and simplicity with which the washing of the coagulate'd product is accomplished. Washing in water is all that is required, whereas in the case of viscose, the large quantities of sulphur in the impure coagulated product must be elimi nated and a number of Washin and bleaching operations must be performed.

The ethylene oxide or other olefne hydrocarbon oxide may be dissolved in benzol or some other non-reactive organic solvent and this solution used to react with the alkali carbohydrate. Aspciic illustration is given hereinafter as Example V. y

Although I prefer to use the etherifying agent in the vapor phase, I may use it in its liquid phase as well as in a solution.. Example VI given hereinafter illustrates the use of an oxide in its liquid form.

The compounds of cellulose and propylene oxide, butylene oxide, and amylene oxide,

may be prepared in a manner similar to the method used for the preparation of the ethylene oxide compound with due regard to the slightV differences in the physical and chemical properties of these oxides. The slight differences in manipulation necessary wilLbe understood by those skilled in the art. The resulting compoundshave those differences in their properties as are to be expected in a series of such compounds. If propylene oxide is used as the etherifying agent, the following example shows how it may be used without freezing. The carbohydrate such as cellulose is treated with alkali by steeping and then removing the excess as hereinbefore described for etherification by ethylene oxide. The resulting alkali cellulose is then treated with a measured amount of propylene oxide (boiling point 35o C. in a closed container at about 35 Cato 40 In a specific instance when 12.6% of propylene oxide was `absorbed, the reaction product as a 6% solution of ether in dilute caustic soda, resulted in a translucent syrup containing many undissolved fibers; at 17.6% there was increasedv solubility but many undissolved fibers; at 22.4% most of the fibers were soluble in a caustic soda solution'which could4 be filtered to a clear solution; and at 28.3% there was perfect solubility. The endv product is an hydroxypropyl ether of cellulose'. The 12.6% propylene oxlde compound may be frozen to form upon melting a practically perfe'ct'sollh tion in dilute caustic soda. The properties of the caustic soda solution of this compound are very similar to thoseof the corresponding ethylene compound, and the films coagulated therefrom are comparable to. those made from the ethylene compound. The

ethylene and propylene compounds may be mixed or formed by the mixed oxides and sometimes used to advantage to replace the separate compounds.

When lusing chemical-wood pulp insteadA of cotton linters to produce ethyleneglycol (di) cellulose ether or the other compounds containing a higher proportion of the etherithe same as before.

fying reagent, I prefer to steep the sheets -of pulp in about 15 parts of 18% to 25% caustic soda solution, and then squeeze to form an alkalicellulose containing from 25% to cellulose. This alkali cellulose is then etheriiied in a closed container with ethylene oxide at room temperature. If ethyleneglycol( di)cellulose ether is desired about 14% of the oxide based on the cellulose content is used. The balance of the procedure is Films and filaments made from the wood pulp compound are weaker when wet than a similar compund made from cotton linters.

If compounds of the carbohydrates not of a cellulosic nature are to be formed, the procedure which is followed is similar to that used with cellulose, giving due regard to the differencesin the chemical and hysical properties of these compounds. uch carbohydrates may be starches, sugars, such as cane sugar, glucose, etc., and include such carbohydrate derivatives as contain hydroxyl groups that are reactive with ethylene oxide. These materials after treating with alkali react with ethylene oxide and propylene oxide and other oxides of the oleline series with great vigor. Thev large amount of heat liberated readily produces a suiiicient rise in temperature to causecharring if the reacting materials are not cooled. A large excess of ethylene oxide renders the product soluble in alcohol. Glucose and cane sugar and other similar carbohydrates may be etherifiedin a like manner to starch. Refrigeration may be used with'the starch as with cellulose but there does not appear to be any advantage gained because all of the products are Water soluble, including the alkali starch.

Throughout the specification etherification has been used to denote the reaction in the presence of alkali between the carbohydrate andthe reacting oxide, or chlorhydrin. The product resulting from the addition of suitable, alkali to the various carbovhydrates is called alkali carboh drate and by reacting the alkali cellulose with propylenc oxide or propylene chlorhydrin are ,hydroxy-propyl others of cellulose, 4those made by reacting alkali cellulose withl glycerol monochlorhydrin are dihydroxypropyl cellulose ethers.

Throughout the specification I use the term alphyl as indicating a radical of the aliphatic series inasmuch as the term alkyl which is sometimes used to make this distinct reference is frequently indicative of both aliphatic and aromatic radicals. The term alphyl is specific tothe aliphatic series in the same manner as aryl is specific to the aromatic series. See Richters Organic Chemistry, Vol. I, page 43, first English edition, 1916. The term caustic alkalies so far as I have reduced the invention to practice refers only tothe hydratcs of sodium and potassium, but in the claims would notexclude the use of hydroxides of other monovalent alkali metals.

Although my process may be applied 'to carbohydrates in general its greatest importance at present seems to be in its application to those carbohydrates that are polysaccharides, especially cellulose. By carbohydrate ilI refer' especially to the natural sugars, starches, and celluloses, and substances related to them. These polysaccharides may contain two or more units of CH10O5. The -cellulose molecule which has not been depolymerized, may contain four such units andmyexperimentsindicatethat four or possibly more of such units will combine with one or more ethylene-oxide molecules to form a compound soluble in dilute caustic soda solution (5% to 15%). The carbohydrates like glucose, which, on the other hand, consist of one such unit, probably united in equi-molecular proportions with the oxide.

It is to be observed that in the process of carrying out the reactions of this invention it may be ,dilicult to control thereaction so that every unit of carbohydrate is similarly combined. with an oxide molecule. Some units of carbohydrate may be deficient in and others may be over-supplied with the oxide, while the average aggregate and the greater percentage of all the aggregates may be similarlycombined. Therefore in the appended claims it is contemplated that the products claimed are not composed entirely, but only predominantly, as vspecied. Whenever the percentage of olefine oxide or alphyl radical is specified, it refers to the added amount rather than the actual amount. This is necessary because of the difiiculties encountered in analyzing the reaction products to determine their exact constitution.

Whenever a reference is made to olefine oxides containing an ethylene oxide group it is intended to cover those oxides in which the oxygen is linked to two adjacent carbon hydrogen groups thereby forming an ethylene 'oxide group within the oleine. Vhenever a non-substituted olefine oxide is referred to this does not cover the homologous oxides of the series. Brophylene oxide may, for example, be called methyl ethylene oxide and may possibly be regarded as a substituted oxide but by me it is not so regarded.

The following specific examples of the invention are given by way of summarizin the invention in its variousmodilications. ther modifications are contemplated by the appended claims.

EXAMPLE I Cellulose-ethylene omale water vn.solu'ble compound suitable for ylms, filaments, elo., containing 20% ethylene ozfle based on original cellulose 100 parts by weight (dry weight) of cotton linters are thoroughly stirred into 1500 parts by Weight of 30% caustic soda solution. After stirring for several minutes to insure thorough wetting of the linters by the caustic soda solution, the linters, now changed into alkali cellulose, are passed through squeeze rolls to remove the excess caustic sodla solution and to increase the cellulose contentof the mixture to about 30%. The mixture after shredding is la. wet, iuffy, fibrous mass. It

vusually is not allowed to'age more than 24 hoursat about 20 C. It isput into a tightly closed reaction chamber in which stirrers keep the alkali- -cellulose thoroughly agitated. Cooling means on the exterior of the reaction chambermay be necessary if the etherifying action is too violent. It is preferable to evacuate the reaction chamber prior to the introduction of the oxide as this hastens the reaction and allows the reaction to proceed more uniformly throughout the alkali cellulose. l/Yhile the alkali cellulose is being stirred vigorously about twenty pounds of gaseous ethylene oxide yare admitted at a rate which does not allow the reacting mass to go over a temperature of 100 C. For the best results the temperature is kept below 45 C. The resulting product is still fluffy' and retains the vphysical megascopic'form and structure of the linters. This product then may be processed in two ways:

(A) To neutralize the excess caustic soda, it-may be treated with a dilute acid, preferably hydrochloric or sulphuric of about 5% y l to 10% strength. If the fibrous compound is-stirred into the acid vigorously, local formation of gel spots may be prevented and' the resulting product retains the fluffy fibrous forms of the librous linters. After the caustic soda is neutralized the product consists of the cellulose-ethylene oxide compou11d,`

hydroxy-ethyl cellulose ether. It may be washed with water to neutrality and then' of air dry cellulose used). There should be enough causticsoda resent in the product so that the diluted so ution containsat least 2% and preferably ill/2% of-caustic soda.

' If thel concentration is below this enough caustic soda is added to bring it up to the desired amount. The cellulose compound forms a clear viscous' solution in the dilute caustic soda. This solution may be filtered to remove any undissolved impurities. If

the solution is too viscous for the next operations it may be aged to reduce this viscosity without decreasing the cellulose concentration. This solution is then passed through suitable dies or formed on suitable shapes to make films, filaments and other products. It then is passed directly into an acid coagulating bath such as 5% sulphuric acid which may contain 15% of sodium sulphate. The caustic soda isv neutralized forming a film, lament'or other article of water insoluble cellulose-ethylene oxide or cellulose hydroxyethyl ether gel. The gel is washed with water and dried. Other operations may be carried out on the formed gel before drying depending upon the use to which it is to be put. Fillers and pigments may be incorporated in the viscous alkaline solution if desirable.

EXAMPLE II Making compounds containing 7% of ethylene oaz'ale using refrigeration the wood pulp it is shredded into a fluy mass. y

As in Example I, the alkali cellulose is put into a tightly closed reaction chamber in which it is stirred vigorously, While about 7 parts by weight of gaseous ethylene oxide are admitted tothe chamber. After the ethylene oxide has reacted completely with the alkalicellulose thereaction mass is removed from the reaction chamber. ,This product may be dissolved in a caustic soda solution of at least about 6%- strength. It contains some undissolved cellulosic products which may not be objectionable for certain purposes, as in certain coating operations. The undissolved cellulosic materials may be made practically entirely soluble by the refrigeratingl operation to. be described.

Enough water is added to the reaction mass.

to bring the caustic soda solution'strength down to' about'4.7 5%. 'Lhe entire-mass is now refrigerated until ",eeze's, 4usually at a temperature of about C. The vfrozen mass is removed from the refrigerating chamber and allowed to melt. Enough caustic soda 1s added prior to melting to produce a final 6% caustic soda solution. The solution which results is clear and viscous.

(B) The concentration of cellulose ether in the final solution produced in (A) is not high enough to make it suitable for the production of films, filaments, and the like. To bring the ether concentration to the desired amount for the production of films and filaments, usually about 8%, thc procedure is modified somewhat. After the etherification is completed, about one-third of the ether reaction mass is removed and neutralized by adding a 5% to 10% solution of hydrochloric or sulfuric acid. -The neutralized ether is washed free of salts after which it is returned to the two-thirds portion which was not treated with acid. The entire mass is 'then diluted with water to bring the caustic soda concentration to 4.75% as in (A). By this procedure the concentration of ether with respect to the caustic soda solution is increased Making compounds containing 1.2% of ethylene amide suitable for )f/ms of highest tramsparencg The procedures as given in Example II are followed except that 12 parts by weight of ethylene. oxide are used and a high grade pulp is used such as is suitable for the viscose type of artificial silk known as rayon. After refrigeration the product may be dissolved in a weaker solution of caustic soda compared to the 6% caustic soda solution needed to dissolve the colnpound containing 7% of ethylene oxide given in Example II. A 4% to 5% caustic soda solution is sufficient.

EXAMPLE IV `Making water soluble compounds from wood pulp and ethylene amide The alkali cellulose is made as described in Example II. After the excess caustic soda soluton is removed from the wood pulp it is allowed' to stand in limited contact with the air for a period of about 24 hours or more. This may be accomplished by putting the alkali cellulose in a container which does not have a tight fitting cover,- thereby also preventing excessive carbonation of the alkali. The alkali cellulose is then etherified with a large amount of ethylene oxide. 75% to 95% or more ethylene oxlde, depending on various factors, is used, this amount being based on the amount of cellulose used in the form of pulp. The resulting compound may now be dissolved in water. The alkali may be neutralized with a mineral acid, such as hydro-` chloric or sulphuric. Goa ulation does not take place. The salts of ydrochloric and sulphuric acid which are formed when the caustic soda is neutralized by these acids may be removed from the compound by dialysis. If acetic acid has been used to neutralize the caustic soda then the resulting sodium acetate may be removed by treating the entire mass with alcohol. Since the sodium acetate is soluble in alcohol this effects a separation from the cellulose compound.

EXAMPLE V Etherificatz'on with ethylene amide dz'ssohved z'n solvents v The alkali cellulose is prepared as described in either Examples I or II. A 20% solution of ethylene oxide in benzol is made. The wet alkali cellulose is submerged in the benzol solution of ethylene oxide for 48 hours at a temperature of about 4 C. after which the excess of benzol and oxide is removed as by centrifuglng or distillation. The resulting compound of cellulose and ethylene oxide is soluble in weak caustic soda solutions and is treated as described in Example I to form other products therefrom. The etherication of alkali cellulose apparently takes place much more slowly in the liquid phase than in the vapor phase.

EXAMPLE VI Ethericatz'on 'with Z/gwd ethylene om'de The alkali cellulose is made as described in Example I. The wet alkali cellulose after squeezing outl the excess of caustic soda is Vsubmerged in liquid ethylene oxide. After being submerged or wetted with the liquid for a period of 20 hours at 4 C. it is removed and the excess ethylene oxide driven off by warming. The resulting product is soluble in dilute caustic soda solutions and may be coagulated as described in Example I and used for various purposes. If it is desirable to increase the temperature so as to cut down the time of etherification pressure vessels must be used.

EXAMPLE VII Making compotmds containing 12.4% of propylene oz'de The alkali cellulose is made as is described in Example I. About 100 parts by weight of fluffy fibrous alkali cellulose is introduced into the reaction chamber. The reaction chamber is evacuated after which the requisite amount of propylene oxide vapor is into keep the reaction chamber at that temcompletely absorbe perature or slightly higher if evacuation is not used. After the ropylene oxide has been by the alkali cellulose the resulting product resembles that after etherification described in Example II. They procedure for isolating this compound and using it in the various forms follows the procedureoutlined in Example II. Compounds containing varyin amounts of propylene oxide may be ma e according to the procedures outlined in Examples I, III, IV, V and VI, having due regard to the differences in the two compounds.;

EXAMPLE VIII Maln'ng compounds of starch and ethylene oz'de About 100 partsby weight of ordinary corn starchycontainin 10% of moisture is mixed with about 2.00 arts by weight of 20% caustic soda solution. The .mixing must be thorough until the reaction is com.- pleted. The alkali starch is then introduced into the treating cylinder with more agitation-and treated with the ethylene oxide'. The ethylene oxide is absorbed by the alkali starch. About 15 to 17 parts b weight of ethylene oxide gives a water so uble, translucent compound that is doughy but sticky in consistency. The excess caustic soda may be dialyzed from the Water soluble starch compound. Acetic acid may be used to neutralize vthe excess caustic soda and the resulting sodium acetate separated from the carbohydrate conipound by ethyl alcohol.

EXAMPLE IX Making cellulose hydroxy-ethyl ether using ethylene chlorhydrz'n Method A: The wet alkali cellulose, made as described in Example I, is introduced into a tightly closed reaction chamber having a stirrer and a false perforated bottom. Into the chamber underneath the false bottom, equal parts of a 20% caustic soda solution and ethylene chlorhydrin of specific gravity 1.15 are introduced. Enough of the twosolutions are used to generate about 20 parts by weight of ethylene oxide. The bottom of the reaction tank is then warmed so as to generate the ethylene oxide more quickly. After the ethylene oxide is completely evolved and has reacted with the alkali cellulose the resulting compound of cellulose and ethylene oxide is removed from the reaction chamber. This compound is similar to that obtained in Example I and the balance of the procedure is the same as that given in Example I.

Method B: In this method the ethylene then introduced into a container which maybe made tight and refrigerated at about 0O C. for about 30 minutes. Six parts by weight of ethylene chlorhydrin of 1.2 specific gravityl are added to the alkali cellulose containing the excess caustic soda solution. The reaction mass is stirred continuously at about 6 C. for onevor two hours and then allowed to come to room temperature and f stirred at this temperature for 24 to 48 hours. Heating to about 30 C. hastens the reaction. The resulting compound is soluble in dilute caustic soda solution.

Method C: The soda cellulose is made as in Example I except that a 40% caustic soda solution is used. After squeezing out the excess caustic soda solutionvthe vmixture is shredded into a Wet fluffy fibrous mass. parts by weight of cellulose areV converted into wet fluffy soda cellulose and treated with about 18. parts by Weight 'of anhydrous or nearly anhydrous ethylene chlorhydrin. This amount of chlorhydrin is equivalent to about 9 parts by weight of ethylene oxide. The mixture is stirred vigorouslyl and preferably in a closed container. The temperature may@ be at room temperature or lower. The reaction is complete Within an hour or two. The resulting reaction productA may then bc diluted with water to bring the caustic soda concentration to about 4.75% NaOH. It may then be frozen as described in Example II. Instead of bringing the caustic soda concentration of the reaction mass to 4.75% it may first be diluted with water to bring the caustic soda concentration to about 6% to 10% after which it is neutralized with an acid. This precipitates the ether, which is washed with Water after which it is again wet with 4.75% NaOH and preferably to a concentration of 8.5% ether so that it may be used for the manufacture of films and filaments. The refrigerating operation then proceeds as in Example II. I

` EXAMPLE X described with the ethylene chlorhydri'n inv EXAMPLE XI Hydrog/-etLyZ-cellulose ether benaoate 100 parts lby Weight of alpha cellulose chemical Wood pulp containing 8.5% moisture is steeped in a 30% caustic soda solution at 18o C. for 45 minutes. The soda cellulose is squeezed to about 350 parts by Weight, shredded, and aged 21.hours at 19o C.' The alkali cellulose is churned in a closed container 21/2 hours With12 parts by Weight of ethylene oxide. Theether isfurther agitated With 15 parts by Weight of benzoylchloride for 30 minutes at room temperature in the presence of an excess of benzol. The resulting alkali-ether-benzoate is centrifuged to remove the benzol, dissolved in 4.75% caustic soda, frozen and thawed as in Examples II or III. A 7.5% solution of the resulting compound is made up in 7.5% solution of caustic soda for use in making films, filaments and other products. yThe process may be reversed, that is, the alkali cellulose may be first benzoylated and then etherified with the ethylene oxide With no appreciable differences in the final product.

The claims of the present application diier from those of the companion applications on this same disclosure in referring broadly to the process of making the new ether, having both general reference to the olefin oxides and specific reference to use of those oxides in the gaseous phase, such as vapors of ethylene oxides. Also this application has special reference to use of organic solutions of the oxides, and the use of oxides homologous to ethylene oxide.

This application is a continuation in part of applicants 4earlier application, Serial 'Number 345,214, filed March 7, 1929, and

which has since become abandoned. Certain subject matter not claimed in the present application is claimed in my copending appli cations Serial Nos. 475,249, 475,250 and 475,251, filed August 14, 1980, and Serial No. 477,753 filed August 25, 1930.

This application is a division of said copending application Serial No. 475,249, filed August 14, 1930.

I claim; l

1. The method of making hydroxy-alphyl ethers of carbohydrates Which comprises bringing Wet alkali carbohydrate and a nonsubstituted ether-forming oxide of a hydrocarnon of the olefine series into intimate contac 2. The method of manufacturing hydroxyalpliyl ethers of carbohydrates which comprises reacting carbohydrates With a caustic alkali solution of sufficient strength to form alkali carbohydrate but containing substantially less than of such alkali and contacting the alkali carbohydrate compound so formed with a non-substituted ether-forming oleline oxide from ethylene l to amylene inclusive.

3. The method of making hydroxy-alphyl ethers of carbohydrates which comprises reacting carbohydrates with a caustic soda solution of sulicient strength to form alkali carbohydrate 'and reacting a non-substituted ether-forming olefine oxide from ethylene to propylene inclusive With the alkali carbohydrate compound so formed in the proportion of at most substantially less than one molecular Weight of said olefine oxide to one carbohydrate unit.

4. The method of making an hydroxyalphyl ether of cellulose which comprises bringing Wet alkali cellulose and a non-substituted ether-forming olefine oxide into intimate contact.

5. The method for making an hydroxyalphyl ether of cellulose which comprises rcacting a non-substituted ether-forming olefine oxide from ethylene to propylene 'with alkali cellulose in the presence of alkali and Water substantially in excess of the alkali. l

' 6. The method of making an hydroxyalphyl ether of cellulose Which comprises bringing into intimate contact Wet soda cellulose and a non-substituted ether-forming oleiine oxide from ethylene to propylene i11- clusive.

7. The method formaking an hydroxyethyl ether of cellulose which comprises reacting alkali cellulose and ethylene oxide in the presence of alkali and Water substantially in excess of the alkali.

8. The method of making an hydroxyethyl ether of cellulose which comprises reacting the vapors of ethylene oxide with wet -soda cellulose.

9. The method for producing an hydroxyalphyl ether of cellulose which is practically insoluble in caustic potashsolutions, which comprises reacting cellulosic raw material which has not been degraded appreciably with an al pliyl etherifying agent in the pres- 'cuce of caustic alkali to form an hydroxyalphyl ether containing two or more cellulose units per alphyl radical.

10. The process of making new cellulose derivatives which comprises first treating cellulosic substances withI caustic alkali to form alkali cellulose, then reacting said alkali cellulose with a non-substituted etherforming oleline oxide, and finally isolating the resulting compound of'cellulose, substantially as described. f

11. Theymethod of forming cellulose derivatives` which comprises subjecting a soda cellulose which is wet with a caustic soda solution substantially less in strength than 50% to reaction with a non-substituted oleine oxide-containing an ethylene oxide group, and

recovering the resulting cellulose compound.

12. HThe process of making hydroxy-alphyl ethers of cellulose which :consists in first reacting alkali solutions'of cellulose derivatives which are soluble in a solution of an alkali with a non-substituted ether-forming oleline oxide from ethylene to amylene inclusive, and then isolating the resulting cellulose compound from the reaction mixture.

13. The 'method of manufacturing hydroxy-alphyl ethers of cellulose from a volatile ether-forming oxide of the'ethylene selow enough to prevent charring.

15. The method of manufacturing hydroxy-ethyl ethers of cellulose which comprises soaking vcellulose in a 14% to a substantially less than 50% caustic alkali solution, expressing the excess solution, and reacting vapors of ethylene oxide with the alkali cellulose so formed..

16. The `process of manufacturing hydroxy-alphyl ethers of cellulose which comprises irst treating cellulosic substances with caustic alkali solution of substantially less than 50% strength to form alkali cellulose, then reacting said alkali cellulose with a nonsubstituted ether-forming oxide of the ethylene series from ethylene to propylene inclusive, bringing the compound formed thereby into dilute caustic soda solution, and finally isolating the ethers of cellulose from the lcaustic soda solution.

17. Themethod of. manufacturing a monohydroxy-.alphyl ether of cellulose which comprises soaking cellulose in a caustic soda solution of at least 14% strength and substantially less than 50% strength, expressing the excess solution and reacting a non-substituted ether-forming oxide of the olefine series from ethylene to propylene inclusive with the alkali cellulose so formed.

' 18. The method of manufacturing hydroxy-ethyll ethers of v cellulose which comprises soaking cellulosic material in caustic soda solution of suliicient strength but substantially less than 50% to form soda cellulose, expressing the excess solution, reacting the vapors of ethylene oxide with the soda cellulose so formed, Washing the compound so formed with a mild acid solution, and following said acid Wash With a Water Wash.

19. The method of producing hydroxyalphyl ethers of cellulose from ethyl to propyl inclusive Which comprises soaking cellulose fibers in a caustic soda. solution of approximately 25% to 35% concentration, expressing the excess caustic solution until the cellulose content has increased to at least 20%, reacting a non-substituted ether-forming olefine oxide from ethylene to propylene with the Wet alkali cellulose so formed, and neutraizing the remaining caustic soda with an acl 20..The method of producing hydroxyethyl ethers of cellulose which comprises steeping cellulosic material in a 14% to substantially less than 50%-caustic soda solution at about room temperature, eliminating excess caustic Solution until the cellulose content has increased to approximately 25% to 35%, reacting ethylene oxide with the Wet alkali cellulose so formed at about room temperature in the proportions of at most substantially less than one molecule of ethylene oxide to one unit of cellulose, bringing said cellulose-ethylene oxide compound formed into solution in caustic soda, coagulating the ether from the caustic soda solution, washing the coagulated product with water, and drying said washed product.

21. The process of producing new cellulose products suitable for the making of filaments 105 and films which comprises treating alpha cellulose with caustic alkali to form alkali cellulose, reacting said alkali cellulose with ethylene oxide inthe ratio of not more than 20% of said oxide to said alpha cellulose, and 11o dissolving said product in a dilute caustic soda solution.

22. The process of making a cellulose reaction product Which is incompletely soluble in a 5% to 15% caustic soda solution at room 115 temperatures, which comprises reacting` wet, soda cellulose with not more than 11% of ethylene oxide based on the Weight of the cellulose.

23. The method of making an hydroxy- 120 alphyl ether of cellulose which comprises subjecting wet alkali cellulose to less than atmospheric pressure and admitting a nonsubstituted ether-forming olefine oxide to contact with said Wet alkali. cellulose while 125 under said reduced pressure. i

24. The method of making hydroxy-alphyl ethers of cellulose from ethyl to propyl inclusive Which comprises steeping cellulose in caustic alkali solution, eliminating the excess 130 alkali solution, subjecting the wet alkali cellulose to less than atmospheric. ressure, reacting a non-substituted etherormlng oleineoxide from ethylene to propylene molusive with alkali cellulose so formed while undeli` said reduced'pressure, and isolating said et er.

25. The method of making an hydroxyalphyl ether of a carbohydrate which comprises dissolving a non-substituted etherforming olefine oxide from ethylene to amylene inclusive in an organic solvent and bringing the resulting solution into contact with wet alkali carbohydrate.

26. The method of making a compound of cellulose .which comprises reacting wet alkali cellulose with a non-substituted ether-forming olefine oxide dissolved in an inert organic solvent of said oxide. y

27. The method of making a compound of cellulose which comprises contacting wet alkali cellulose with ethylene voxide dissolved in an inert-organic solvent of said oxide.

. 28. The method of making an hydroxylpropyl ether of cellulose which comprises reacting the vapors of propylene oxide with wet soda cellulose.

In Ytestimony whereof, I have subscribed my name.

a ARLIE W. sc HoRGER.- 

